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/*
* A virtio device implementing a hardware random number generator.
*
* Based on virtio-rng.c of QEMU project
* Copyright 2012 Red Hat, Inc.
* Copyright 2012 Amit Shah <amit.shah@redhat.com>
*
* Copyright 2022-2023 Virtual Open Systems SAS.
*
* This work is licensed under the terms of the GNU GPL, version 2 or
* (at your option) any later version. See the COPYING file in the
* top-level directory.
*/
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdbool.h>
#include <sys/param.h>
/* Project header files */
#include "virtio_loopback.h"
#include "virtio_rng.h"
#ifdef DEBUG
#define DBG(...) printf("virtio-rng: " __VA_ARGS__)
#else
#define DBG(...)
#endif /* DEBUG */
bool is_guest_ready(VirtIORNG *vrng)
{
VirtIODevice *vdev = vrng->parent_obj;
if (virtio_queue_ready(vrng->vq)
&& (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
return true;
}
return false;
}
size_t get_request_size(VirtQueue *vq, unsigned quota)
{
unsigned int in, out;
virtqueue_get_avail_bytes(vq, &in, &out, quota, 0);
return in;
}
void virtio_rng_set_status(VirtIODevice *vdev, uint8_t status)
{
VirtIORNG *vrng = vdev->vrng;
vdev->status = status;
/* Something changed, try to process buffers */
virtio_rng_process(vrng);
}
/* Send data from a char device over to the guest */
void chr_read(VirtIORNG *vrng, const void *buf, size_t size)
{
VirtIODevice *vdev = vrng->parent_obj;
VirtQueueElement *elem;
size_t len;
int offset;
if (!is_guest_ready(vrng)) {
return;
}
vrng->quota_remaining -= size;
offset = 0;
while (offset < size) {
elem = virtqueue_pop(vrng->vq, sizeof(VirtQueueElement));
if (!elem) {
break;
}
len = qemu_iov_from_buf(elem->in_sg, elem->in_num,
0, buf + offset, size - offset);
offset += len;
virtqueue_push(vrng->vq, elem, len);
/*
* TODO: We need tp free the elem
*
* g_free(elem);
*/
}
virtio_notify(vdev, vrng->vq);
if (!virtio_queue_empty(vrng->vq)) {
/*
* If we didn't drain the queue, call virtio_rng_process
* to take care of asking for more data as appropriate.
*/
virtio_rng_process(vrng);
}
}
const char test_str[64] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
60, 61, 62, 63};
void virtio_rng_process(VirtIORNG *vrng)
{
size_t size;
unsigned quota;
if (!is_guest_ready(vrng)) {
return;
}
if (vrng->quota_remaining < 0) {
quota = 0;
} else {
quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX);
}
size = get_request_size(vrng->vq, quota);
size = MIN(vrng->quota_remaining, size);
if (size) {
chr_read(vrng, &test_str, size);
}
}
void handle_input(VirtIODevice *vdev, VirtQueue *vq)
{
virtio_rng_process(vdev->vrng);
}
static void virtio_dev_class_init(VirtIODevice *vdev)
{
vdev->vdev_class = (VirtioDeviceClass *)malloc(sizeof(VirtioDeviceClass));
vdev->vdev_class->parent = vdev;
vdev->vdev_class->set_status = virtio_rng_set_status;
}
void virtio_rng_init(VirtIODevice *vdev)
{
VirtIORNG *vrng = (VirtIORNG *)malloc(sizeof(VirtIORNG));
vdev->vrng = vrng;
vrng->parent_obj = vdev;
vrng->vq = vdev->vq;
vrng->quota_remaining = LONG_MAX;
/* Prepare dev_class */
virtio_dev_class_init(vdev);
}
void virtio_rng_realize(void)
{
/* prepare procy and virtio dev*/
proxy = (VirtIOMMIOProxy *)malloc(sizeof(VirtIOMMIOProxy));
virtio_dev_init(global_vdev, "virtio-rng", 4, 0);
virtio_rng_init(global_vdev);
global_vdev->vq = virtio_add_queue(global_vdev, 8, handle_input);
global_vdev->host_features = 0x39000000;
*proxy = (VirtIOMMIOProxy) {
.legacy = 1,
};
}
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